iPhone/Mac: Typing in a password is by no means a complicated process, but if you'd like to add an extra layer of security, Knock is an app for iPhone and Mac that uses your phone to unlock your computer.

Knock uses Bluetooth to pair your Mac and your phone together. Then, when you tap on your phone two times, it sends a signal to your computer to unlock it and log in. Knock uses Bluetooth Low Energy so it doesn't suck up that much battery life when it's on. It's simple, but it works surprisingly well.